From 2003 to 2004 — a year tribal police saw the worst increase in meth use — criminal charges for drug possession on the Wind River Reservation increased 353 percent. During that period, assaults tripled, theft nearly doubled and child abuse increased by 85 percent.

Arrests and several convictions, including the sentencing of one of the cell leaders to life in prison in July, have slowed the advance of the drug here, authorities say, but many tribe members say they've seen little effect.

"There are so many people using, you can see them just walking around the store" here, said Georgia O'Hair, a reservation treatment counselor and former meth addict.

"Their skin is ashen. Those repetitive movements and jerks. It's what addicts call tweaking," she said.

The new alcohol

Investigators say the Sinaloan Cowboys' success here offers a frightening picture of meth's rapid rise in Indian Country, providing a snapshot into how the stimulant has grown to rival alcohol as the drug of choice on reservations throughout the West.

Experts say that about half of addictions on reservations still are to alcohol.

But meth has moved so quickly that it has left tribal governments across the region reeling. Struggling to catch up, some leaders even have ceded fiercely protected tribal sovereignty in exchange for help.

Two major busts on the Wind River in the past two years were the result of an unprecedented law enforcement coalition that included the Drug Enforcement Administration, the Wyoming Division of Criminal Investigation, local tribal police and the Bureau of Indian Affairs.

Sprawling across a rolling prairie at the foot of the Wind River Mountains, the reservation appears the last place that would attract Mexican drug gangs that flourish in the immigrant barrios of America's major cities.

Rural and remote, the reservation is home to 6,400 American Indians split mostly between two tribes, the Eastern Shoshone and the Northern Arapaho. Apart from Riverton, which is largely white, the reservation's few small towns are destitute collections of mostly sagging homes and rundown trailers.

A 1998 tribal study found that 38 percent of American Indian adults on the Wind River were unemployed and that 57 percent lived in poverty.

But from the perspective of gang members, the reservation had an important plus: jurisdictional barriers normally prevent state and local police from operating on tribal lands. And despite the apparent poverty of Indian country, many tribal members receive monthly checks from mineral royalties or other tribal income.

Members of the Mexican gang discovered that alcohol sales on other reservations spiked after members received their checks, sources told investigators, and they believed they could tap into that cash.